Chesapeake Bay impact structure: Morphology, crater fill, and relevance for impact structures on Mars

摘要: The late Eocene Chesapeake Bay impact structure (CBIS) on the Atlantic margin of Virginia is one largest and best-preserved "wet-target" craters Earth. It provides an accessible analog for studying processes in layered wet targets volatile-rich planets. CBIS formed a target water, weak clastic sediments, hard crystalline rock. buried consists deep, filled central crater, 38 km width, surrounded by shallower brim known as annular trough. trough partly collapse which expanded to ~85 diameter. Such extensive collapse, addition excavation processes, can explain "inverted sombrero" morphology observed at some targets.The distribution crater-fill materials related morphology. Suevitic breccia, including pre-resurge fallback deposits, found crater. Impact-modified fluidization water-saturated sand silt-clay, occur Allogenic sediment-clast interpreted ocean-resurge overlies other impactites covers entire crater beneath blanket postimpact sediments.The formation chaotic terrains Mars attributed due release volatiles from thick deposits. Some flat-floored rimless depressions with infill these are that farther than expected similar-sized complex solid targets. Studies provide insights into expansion their links volatiles.